CRT Electron Lifetime and Purity Measurement Updates Richie Diurba diurb001@umn.edu 1/20
Progress since January Collaboration Meeting • Based on comments from reviewers, the electron lifetime measurements were worked on to look at a week of beam data-taking. • Measurements were made of a rise in purity and of Q c / Q a . • Throughout this data-taking τ > 10 ms Quantifying Lifetime • Lifetime as a function of time: Q ( t ) = Q o e − t /τ lifetime • Lifetime as a ratio of charge on the cathode and anode: Q a = Q ( t tot drift ) = e − ttot drift /τ lifetime Q c Q (0) 1 • Purity as a function of lifetime at approx. 500 V/cm: N 0 2 = 500 ppt ms τ 2/20
Introduction to Measurement Basics (the x-coordinate in the diagram is pointing in the negative direction) • CRT did not come alive until end of October, 2018 (Approx. run 5759). • Because of the beam triggering, CRT tracks that enter BL dominate. This means we could not measure BR TPC. 3/20
CRT Reconstruction Matching tracks • Match to a TPC track by minimizing the displacement between the CRT hit to the TPC track, if we extrapolate the TPC track onto the CRT hit’s position in Z. • Good purity ( > 99.9% in MC) Example of CRT reconstruction on a handful of strips on two US modules and two DS modules. Getting hits for lifetime studies • Collect matched track hits between 230 < z < 460 and 200 < y < 400 • Take hit integrals and correct them for time ( t hit − t crt ) • Measure dQ/dx by taking the hit integral and dividing by the step length to the next collection plane hit. • Correct based on the electric field and histogram integral within 0.1 ms time bin. 4/20
Calibrating Hits for the Space Charge Effect To calibrate the electric field’s SCE displacements, we do the following: dQ / dx ( E nom ) • c sce = dQ / dx ( E calib sce ) • dQ corr / dx = c sce ∗ dQ uncalib / dx Electric field calibrated is found by taking the track point from the CRT track position and feeding that coordinate into Mike’s data driven map. Correction coefficient 5/20
Improvements to the Analysis • CRT analyzer code was optimized to maximize the amount of data processed. • The Landau-Gauss fitter was tuned thanks to the help of Tingjun and Roberto. • The amount of events per 100 us slice in time for measuring the MPV of dQ/dx was increased from 100 hits to 1000 hits. This ensures stability but it did get rid of a day from beam data-taking. • YZ corrections were taken out as we found issues plotting dQ/dx as a function of Z. We are investigating this. Old electron lifetime fit (left) and current (right) for run 5759 6/20
Increase in Purity Observed First Week of November 2018 • All errors are statistical and are modulated on a run-by-run basis so each measurement has a Chi2/dof approx. at 1. Run 5759 (left) and run 5770 (right) 7/20
Increase in Purity Observed First Week of November 2018 Run 5773 (left) and run 5776 (right) 8/20
Increase in Purity Observed First Week of November 2018 • I also think you get the point so I will be skipping a few runs, see backup for the rest. Run 5833 (left) and run 5841 (right) 9/20
Electron Lifetime Measurements • There was not enough data for 11/6/2018 to make a precise electron lifetime measurement. 10/20
Electron Lifetime to Q c / Q a Q a = e − 2 . 3 ms Q c • τ • 2.3 ms value taken from cathode-anode crossing study by Ajib and Tianle. Charge ratio from cathode to anode. This plot is included in the paper. 11/20
Translating to Impurity Concentration From Craig Thorn (BNL) using data from Bakale. 12/20
Impurity Measurement • N O 2 = 500 ppt ms at approx. 500 V/cm electric field (C. Thorn, ”Catalogue of τ Liquid Argon properties”, MicroBooNE doc:412) Impurity estimate for November 2018 13/20
November 2019 Runs Since beam data-taking, I have not been able to see a run since a purity recovery from late October that does not have minimal to no electron attenuation. Run 10374 lifetime measurement for BR with data-driven interpolated map (left) and Run 10374 BR with Ajib and Tianle’s Cathode-And-Anode map (right) 14/20
November 2019 Runs Before, we use the hit integral from the ADC fitting. Jianming suggested maybe summing the ADC signal would give a more accurate, non-infinite lifetime. This was not observed. Run 10374 lifetime measurement for BR with data-driven interpolated map (left) and Run 10374 BR with Ajib and Tianle’s Cathode-And-Anode map (right) 15/20
Conclusion • A week of data was analyzed during a rise in purity. This analysis was included in the electron lifetime portion of the paper. • Lifetime was always τ > 10 ms • Using Thorn’s interpretation of Bakale, contamination was measured to be consistently below 50 ppt oxygen equivalent. • Jianming and I are currently working on combining the CRT measurement with the purity monitor measurement so we can calibrate purity monitor data given the HV differences between the two. 16/20
Backup Slides 17/20
More Electron Lifetime Measurement Plots Run 5780 (left) and run 5796 (right) 18/20
More Electron Lifetime Measurement Plots Run 5780 (left) and run 5796 (right) 19/20
More Electron Lifetime Measurement Plots Run 5814 (left) and run 5824 (right) 20/20
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